Turbocharger



NOV. 30, 1954 M, L, LAND TAL 2,695,767

TURBOCHARGER Filed March 25, 1951 A IHIM Q Whelgmp I l l Yw. vesrsn? lf"Enum' 74M, Mmm/JAM THE/l? Hrm/eus P:

United States Patent O TURBOCHARGER Malcolm L. Land and Sylvester F.Brust, Jeannette, Pa.,

assignors to Elliott Company, Jeannette, Pa., a corporation ofPennsylvania Application March 23, 1951, Serial No. 217,192

Claims. (Cl. 253-78) This invention relates to high temperature rotatingmachinery, and more particularly to gas turbine nozzle rings and themanner in which they are connected to the turbine inlet casings,especially of turbochargers.

In the operation of turbochargers, for example, many of them are subjectto frequent cyclic temperature variations because they are used withengines that are frequently started and stopped. One example of such asituation is found in diesel locomotives. In turbochargers a gas turbineinlet casing has its inner end connected to a stationary nozzle ring.The nozzle ring has a hub from which guide blades project, the outerends of the blades being mounted in an encircling shroud ring. The hubis rigidly connected to the inlet casing, and it is preferred to connectthe shroud ring to the same casing in such a way that it can not moveaxially but can expand radially relative to the casing when the nozzlering is heated faster than the casing. Even with such provision forexpansion, however, the guide blades often buckle and fracture wherethey are attached to the hub and shroud. This is because the blades,being much thinner than the hub and shroud ring of the nozzle ring, heatand cool much more rapidly under cyclic temperature variations then theadjoining parts of the nozzle ring. Also, the nozzle ring hub is subjectto a radial temperature gradient, particularly during the cyclictemperature variations. This temperature gradient often is severe enoughto cause cracking of the hub.

`It is among the objects of this invention to provide a gas turbine inwhich the nozzle ring guide blades will not fail due to cyclictemperature variations, in which the danger ofthe radial temperaturegradient in the nozzle ring hub causing cracking of the hub is greatlyreduced, and in which the nozzle ring is attached to the inner end ofthe turbine inlet casing in a simple but effective way.

In accordance with this invention a gas turbine nozzle ring, whichincludes guide blades mounted between a hub and an annular shroud, hasits hub fastened to the inner end of the turbine inlet casing. Theoutside of the shroud is provided with a plurality of circumferentiallyspaced radial lugs extending around it and slidably received in innerradial recesses in lugs extending across the shroud lugs from the innerend of the casing. The cooperating lugs hold the shroud against thecasing, but the recesses are deep enough to leave space between theouter surfaces of the shroud lugs and the surrounding surfaces of thecasing lugs to permit movement of the shroud lugs outward in therecesses when the nozzle ring expands radially relative to the casing.Furthermore, the shroud is provided at circumferentially spaced pointswith slits extending across it between its blades to separate it intosegments that can be moved radially outward by the blades when theblades expand faster than the shroud, as they do when the turbine issubject to frequent cyclic temperature variations. Also, the nozzle ringhub is provided with a plurality of circumferentially spaced radialslots extending outward from its inner diameter part way through the hubto help keep the hub from cracking during cyclic temperature variations.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FigA l is a side view of a turbochargerwith its turbine inlet casing shown in section; Fig. 2 is a crosssection taken on the line II-II of Fig. l, but with the turbine wheelremoved; and Fig. 3 is a fragmentary cross section taken on the lineIll-III of Fig. 2.

Referring to the drawings, the turbocharger includes a ice blower casing1 through which air is driven at high velocity by an impeller (notshown) mounted on one end of a shaft that is driven by a turbine wheel 2on its opposite end. The turbine wheel is located in a turbine casing 3,to which hot gases are delivered through passages 4 (Fig. 3) in an inletcasing 5 which is axially aligned with the turbine wheel. In order toproperly direct the gases against the blades 7 of the wheel, a nozzlering 8 is disposed between the inner end of the inlet casing and thewheel. This ring has a hub 9 which is connected by bolts 10 to the inletcasing. The hub supports a series of guide blades 11 that are curvedtransversely and inclined to its axis. The outer ends of these bladesare mounted in a shroud ring 12 which extends inward across the outerends of the turbine wheel blades 7.

When this turbocharger is used where it is frequently started andstopped, the hub 9 of the nozzle ring is subject to a radial temperaturegradient that may be severe enough to cause it to crack. The severity ofthis condition can be reduced materially by providing the hub with aplurality of radial slots 14 extending from its inner diameter outwardpart way through the hub, as shown in Fig. 2. The outer ends of theslots terminate in circular holes 15 of rather large diameter extendingthrough the hub. These holes minimize the possibility of crackprogression beyond the outer ends of the slots. For best results, it ispreferred to have one slot midway between each pair of bolts 10.

ln accordance with this invention, means also is provided to permitexpansion and contraction of the nozzle guide blades 11 radially of thenozzle ring without restraint by the shroud ring and without the shroudring separating from the casing. For this purpose the outside of shroud12 is provided with a plurality of circumferentially spaced radial lugs17 that extend around it short distances, preferably at the end of theshroud next to the inlet casing. The outer surfaces of these lugs formarcs of a circle concentric with the shroud ring. Also, the inner end ofthe inlet casing has a lug 18 extending across each of the shroud lugsand provided with an inner radial recess 19 that receives the adjoiningshroud lug. The radial surfaces of the recesses and shroud lugs farthestfrom the inlet casing engage each other to hold the shroud in tightsliding engagement with the inner end of the casing. As shown in Fig, 3,the lug recesses 19 are deep enough to leave spaces between the arcuateouter surfaces of the shroud lugs and the surrounding surfaces of thecasing lugs. These spaces allow unrestrained expansion of the nozzlering radially relative to the inlet casing.

.A further feature is that the nozzle ring shroud 12 is provided atcircumferentially spaced points with slits 21 extending diagonallyacross it between adjacent pairs of guide blades 11 to separate theshroud ring into segments. Consequently, whenever the guide bladesexpand radially of the nozzle ring faster than the shroud ring, thoseblades can move the different segments of the shroud bodily outwardradially of the nozzle ring, the shroud lugs sliding outward in thecasing lug recesses 19 to permit such movement. It is preferred to soposition each slit 21 that it will pass through one of the shroud lugs,so that the lug end of the slit will be straddled by the adjoiningcasing lug. In this way both ends of each segment of the shroud ring areheld against the inner end of the inlet casing by the casing lugs at theopposite ends of that segment.

In assembling the nozzle ring with the inlet casing, the ring is placedagainst the inner end of the casing with the shroud lugs between thecasing lugs. Then the nozzle ring is turned on its axis until the shroudlugs have slid into the casing lug recesses. At that time the bolt holesin the nozzle ring hub are in alignment with the bolt holes in the inletcasing, and bolts 10 can be inserted and tightened to hold the hubtightly against the casing and to prevent the nozzle ring from rotatingout of position. No bolts are required for holding the shroud ringagainst the inlet casing, for the interengaging lugs will do that,

According to the provisions of the patent statutes, we have explainedthe principle of our invention and have illustrated and described whatwenow consider to represent its best embodiment. However, we desire tohave it understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specitically illustratedand described.

We claim:

l. In high temperature rotating machinery, a gas turbine inlet casing, anozzle ring at the inner end of the casing including guide bladesmounted between a hub and an annular shroud, and means fastening the hubto the casing, the outside of the shroud being provided with a pluralityof circumferentially spaced radial lugs extending around it, the innerend of the casing having a lug extending across each of the shroud lugsand provided with an inner radial recess slidably receiving theadjoining shroud lug to hold the shroud against the inner end of thecasing, said recesses being deep enough to leave space between the outersurfaces of the shroud lugs and the surrounding surfaces of the casinglugs to permit movement of the shroud lugs outward in the recesses whenthe nozzle ring expands radially relative to said casing, and the shroudbeing provided at circumferentially spaced points with slits extendingacross it between said blades to separate it into segments that can bemoved radially outward by the blades when the blades expand faster thanthe shroud, the shroud lugs being spaced far enough apart to accommodatethe casing lugs between them in case the nozzle ring is rotated relativeto the inlet casing after said hub has been unfastened from the casing,whereby the shroud lugs can be disconnected from the casing lugs.

2. In high temperature rotating machinery, a gas turbine inlet casing, anozzle ring engaging the inner end of the casing including guide bladesmounted between a hub and an annular shroud, and means fastening the hubto the casing, the outside of the shroud being provided at its casingend with a plurality of circumferentially spaced radial lugs extendingsubstantially parallel to the ends of the shroud, the inner end of thecasing having a lug extending across each of the shroud lugs andprovided with an inner radial recess slidably receiving the adjoiningshroud lug to hold the shroud against the inner end of the casing, saidrecesses being deep venough to leave space between the outer surfaces ofthe shroud lugs and the surrounding surfaces of the casing lugs topermit movement of the shroud lugs outward in the recesses when thenozzle ring expands radially relative to-said casing, and the shroudbeing provided at circumferentially spaced points with slits extendingacross it between said blades to separate it into segments thatlcan bemoved radially outward by the blades when the blades expand faster thanthe shroud, the shroud lugs being spaced far enough apart to accommodatethe casing lugs between them in case the nozzle ring is rotated relativeto the inlet casing after said hub has been unfastened from the casing,whereby the shroud lugs can be disconnected from the casing lugs.

3. In high temperature rotating machinery, a gas turbine inlet casing, anozzle ring at the inner end of the casing including guide bladesmounted between a hub and an annular shroud, and means fastening the hubto the casing, the outside of the shroud being provided with a pluralityof circumferentially spaced radial lugs extending around it, the innerend of the casing having a lug extending -'across each of the shroudlugs and provided with an inner radial recess slidably receiving theadjoining shroud lug to hold the shroud against the inner end of thecasing, said recesses being deep enough to leave space between the outersurfaces of the shroud lugs and the surrounding sur faces of the casinglugs to permit movement of the shroud lugs outward in the recesses whenthe nozzle ring expands radially relative to said casing, and the shroudbeing provided at circumferentially spaced points with slits extendingacross it between said blades and through said shroud lugs to separatethe shroud into segments that can be moved radially outward by theblades when the blades expand faster than the shroud, both parts of eachslit shroud lug being received in the recess of the casing lug engagingthat shroud lug, whereby each casing lug straddles one of said slits.

4. In high temperature rotating machinery, a gas turbine inlet casing, anozzle ring at the inner end of the casing including guide bladesmounted between a hub and an annular shroud, and means fastening the hubto the casing, the hub being provided with a' plurality ofcircumferentially spaced radial slots extending outward from its innerdiameter only part way through the hub, the outside of the shroud beingprovided with a plurality of circumferentially spaced radial lugsextending around it, the inner end of the casing having a lug extendingacross each of the shroud lugs and provided with an inner. radial recessslidably receiving the adjoining shroud lug to hold the shroud againstthe inner end of the casing, said recesses being deep enough to leavespace between the outer surfaces of the shroud lugs and the surroundingsurfaces of the casing lugs to permit movement of the shroud lugsoutward in the recesses when the nozzle ring expands radially relativeto said casing, and the shroud being provided at circumferentiallyspaced points with slits extending across it between said blades toseparate it into segments that can be moved radially outward by theblades when the blades expand faster than the shroud.

5. In high temperature rotating machinery, a gas turbine inlet casing, anozzle ring at the inner end ofv the casing including guide bladesmounted between a hub and an annular shroud, and means fastening the hubto the casing, the hub being provided with a plurality ofcircumferentially spaced holes through it and radial slots extendingfrom the holes to the inside of the hub, the outside of the shroud beingprovided with a plurality of circumferentially spaced radial lugsextending around it, the inner end of the casing having a lug extendingacross each of the shroud lugs and provided with an inner radial recessslidably receiving the adjoining shroud lug to hold the shroud againstthe inner end of the casing, said recesses being deep enough to leavespace between the outer surfaces of the shroud lugs and the surroundingsurfaces of the casing lugs to permit movement of the shroud lugsoutward in the recesses when the nozzle ring expands radially relativeto said casing.

References Cited in the ile of this patent UNITED STATES PATENTS NumberName Date 596,792 Schmidt Jan. 4, 1898 1,267,872 Junggren May 28, 19181,378,464 Junggren May 17, 1921 1,670,452 Kaehler May 22, 1928 2,296,702Butler et al. Sept. 22, 1942 2,527,445 Pentheny Oct. 24, 1950 2,625,013Howard et al. Jan. 13, 1953 FOREIGN PATENTS Number Country Date 107,788Sweden June 29, 1943 726,951 Germany Oct. 23, 1942

